Actually, with such a short time, the subway and airtrain would probably be your safest option, though it's just as prone to delays as traffic is. Driving will take about 40min to 1hr, 15min. Half of that is Manhattan alone. Either way, you'd be lucky to be at the gate by 6pm. I'd check Google maps for travel time info the second the show ends to see which would be faster.
Also, bear in mind, that the TSA may not be operating Pre-Check at all terminals. When they are understaffed, they often make you go through the regular security line,, and the pre-check simply allows you to pass through the metal detector instead of the body scanner. Even though you do not have any bags, you still have to put keys, phones, etc. through the scanner.
Another thing to note is the boarding time of your flight. Since most airlines close the doors about 10-minutes before the scheduled departure time, some minutes before that they will start removing passengers who have not boarded and assign those seats to standby passengers.
Can you do it? Possibly. But there is no definite positive answer to your question. There are too many x factors that could delay you. And that's not including any unlikely delay at the performance (late start, stopped show, etc.). Is there a later flight you can catch if you miss this one?
